The ability to reduce the surface tension of water is of great importance in waterborne coatings, inks, adhesives, and agricultural formulations because decreased surface tension translates to enhanced substrate wetting in actual formulations. Surface tension reduction in water-based systems is generally achieved through the addition of surfactants. Performance attributes resulting from the addition of surfactants include enhanced surface coverage, fewer defects, and more uniform distribution. Equilibrium surface tension performance is important when the system is at rest. However, the ability to reduce surface tension under dynamic conditions is of great importance in applications where high surface creation rates are utilized. Such applications include spraying, rolling and brushing of coatings or spraying of agricultural formulations, or high speed gravure or ink-jet printing. Dynamic surface tension is a fundamental quantity which provides a measure of the ability of a surfactant to reduce surface tension and provide wetting under such high speed application conditions.
Traditional nonionic surfactants such as alkylphenol or alcohol ethoxylates, and ethylene oxide (EO)/propylene oxide (PO) copolymers have excellent equilibrium surface tension performance but are generally characterized as having poor dynamic surface tension reduction. In contrast, certain anionic surfactants such as sodium dialkyl sulfosuccinates can provide good dynamic results, but these are very foamy and impart water sensitivity to the finished coating.
Surfactants based on acetylenic glycols such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol (1) and its ethoxylates (2) are known for their good balance of equilibrium and dynamic surface-tension-reducing capabilities with few of the negative features of traditional nonionic and anionic surfactants. ##STR2##
For many applications it would be desirable to produce acetylenic diol derivatives which have alternative properties. For example, in applications in which excellent dynamic performance is required, it is often desirable to have a surfactant which has higher critical aggregation concentration (solubility limit or critical micelle concentration) because higher bulk surfactant concentrations lead to a higher diffusive flux of surfactant to newly created surface, and consequently lower dynamic surface tension. Traditionally, acetylenic diol surfactants with higher water solubility have been obtained by reaction of the parent with ethylene oxide; greater degrees of ethoxylation provide greater water solubility. Unfortunately, increasing the level of ethoxylation also introduces a tendency to foam, introducing inefficiencies during formulation, defects during application, and process issues in other applications.
Low dynamic surface tension is of great importance in the application of waterborne coatings. In an article, Schwartz, J. "The Importance of Low Dynamic Surface Tension in Waterborne Coatings", Journal of Coatings Technology, September 1992, there is a discussion of surface tension properties in waterborne coatings and a discussion of dynamic surface tension in such coatings. Equilibrium and dynamic surface tension were evaluated for several surface active agents. It is pointed out that low dynamic surface tension is an important factor in achieving superior film formation in waterborne coatings. Dynamic coating application methods require surfactants with low dynamic surface tensions in order to prevent defects such as retraction, craters, and foam.
Efficient application of agricultural products is also highly dependent on the dynamic surface tension properties of the formulation. In an article, Wirth, W.; Storp, S.; Jacobsen, W. "Mechanisms Controlling Leaf Retention of Agricultural Spray Solutions"; Pestic. Sci. 1991, 33, 411-420, the relationship between the dynamic surface tension of agricultural formulations and the ability of these formulations to be retained on a leaf was studied. These workers observed a good correlation between retention values and dynamic surface tension, with more effective retention of formulations exhibiting low dynamic surface tension.
Low dynamic surface tension is also important in high-speed printing as discussed in the article "Using Surfactants to Formulate VOC Compliant Waterbased Inks", Medina, S. W.; Sutovich, M. N. Am. Ink Maker 1994, 72 (2), 32-38. In this article, it is stated that equilibrium surface tensions (ESTs) are pertinent only to ink systems at rest. EST values, however, are not good indicators of performance in the dynamic, high speed printing environment under which the ink is used. Dynamic surface tension is a more appropriate property. This dynamic measurement is an indicator of the ability of the surfactant to migrate to a newly created ink/substrate interface to provide wetting during high speed printing.
U.S. Pat. No. 5,098,478 discloses water-based ink compositions comprising water, a pigment, a nonionic surfactant and a solubilizing agent for the nonionic surfactant. Dynamic surface tension in ink compositions for publication gravure printing must be reduced to a level of about 25 to 40 dynes/cm to assure that printability problems will not be encountered.
U.S. Pat. No. 5,562,762 discloses an aqueous jet ink of water, dissolved dyes and a tertiary amine having two polyethoxylate substituents and that low dynamic surface tension is important in ink jet printing.
In applications which require good dynamic performance and low foaming, acetylenic glycol-based surfactants have become industry standards. The following patents and articles describe various acetylenic alcohols and their ethoxylates as surface active agents:
U.S. Pat. No. 3,268,593 and Leeds, et al, I&EC Product Research and Development 1965, 4, 237, disclose ethylene oxide adducts of tertiary acetylenic alcohols represented by the structural formula ##STR3##
wherein R.sub.1 and R.sub.4 are alkyl radicals having from 3-10 carbon atoms and R.sub.2 and R.sub.3 are methyl or ethyl and x and y have a sum in the range of 3 to 60, inclusive. Specific ethylene oxide adducts include the ethylene oxide adducts of 3-methyl-1-nonyn-3-ol, 7,10-dimethyl-8-hexadecyne-7,10-diol; 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 4,7-dimethyl-5-decyne-4,7-diol. Preferably, the ethylene oxide adducts range from 3 to 20 units. Also disclosed is a process for the manufacture of materials of this type using trialkylamine catalysts.
U.S. Pat. No. 4,117,249 discloses 3 to 30 mole ethylene oxide (EO) adducts of acetylenic glycols represented by the structural formula ##STR4##
wherein R is hydrogen or an alkenyl radical. The acetylenic glycols are acknowledged as having utility as surface active agents, dispersants, antifoaming nonionic agents, and viscosity stabilizers.
U.S. Pat. No. 5,650,543 discloses ethoxylated acetylenic glycols of the form ##STR5##
where x and y are integers and the sum is from 2-50. These surfactants are notable because they impart an ability to formulate coating and ink compositions capable of high speed application.
JP 2636954 B2 discloses propylene oxide adducts of formula ##STR6##
where R=C1-8 alkyl; m+n=integer 1 to 100. These compounds are prepared by reacting acetylenic glycols and propylene oxide in the presence of Lewis acid catalysts such as BF.sub.3. It is stated that amine catalysts are inactive for the addition of propylene oxide to acetylenic diols. The propylene oxide adducts are said to be useful as wettability improvers for antirust oil, antifoamers, spreaders for pesticides, and wetting agents for adhesives. They are effective in improving wettability of oils and have improved antifoaming ability.
JP 2621662 B2 describes dye or developing agent dispersions for thermal recording paper containing propylene oxide (PO) derivatives of an acetylenic diol of the form ##STR7##
where R1 and R2 are --CH3, --C2H5, --C4H9; R3 and R4 are --(OC3H4)mOH, or --OH where m is an integer 1-10.
JP 04071894 A describes coating solutions containing a dispersion of a colorless electron donating dye precursor and a dispersion of developer. At least one of them contains at least one type of wax having a melting point of at least 60.degree. C. and at least one EO or PO derivative of an acetylenic diol of the formula ##STR8##
where R1 and R4 each represent methyl, ethyl propyl, or butyl and R2 and R3 are each --(OC2H5)nOH, or --(OC3H6)nOH (n is 1-10), or OH, mixed and dispersed.
JP 2569377 B2 discloses a recording material containing dispersions of a substantially colorless electron donating dye precursor and a developer. When at least one of these dispersions is prepared, at least one of the compounds ##STR9##
where R.sup.3 and R.sup.6 =methyl, ethyl, propyl or butyl; and R.sup.4 and R.sup.5 =(OC.sub.2 H.sub.4).sub.m OH, --(OC.sub.3 H.sub.6).sub.m OH (where m=an integer of 1-10) or --OH is added.
JP 09150577 A discloses a heat sensitive recording medium which contains in the heat sensitive layer a leuco dye and 0.1-1.0 wt % of an ethoxylate or propoxylate of an acetylenic glycol of the form ##STR10##
where R.sup.1 =methyl, ethyl, propyl or butyl; R.sup.2 =hydrogen or methyl; and n and m=1-10.
JP 04091168 A discloses silica which has been surface treated with compounds of the form ##STR11##
where R1=1-8C alkyl, A=2-3C alkylene glycol residue, R1 and A in a molecule may be the same or different, x and y=each an integer of 0-25.
JP 06279081 A describes a manufacturing process for a cement mortar-concrete hardening material to which 0.5-10 wt. % an acetylenic alcohol or diol alkoxylate is added together with fluorine group surfactants and/or silicon group surfactants. The acetylenic material can be expressed by the formula ##STR12##
where R1=H or --C(R2)(R3)(O(AO)nH); R2 and R3=1-8C alkyl radicals, A=2-3C alkylene radicals and n=0-30.
JP 03063187 A discloses the use of acetylenic glycol ethylene oxide and/or propylene oxide addition products in concentrated aqueous fountain solution compositions for offset printing. In one example, the 8 to 12 mole ethylene oxide/1 to 2 mole propylene oxide adduct of 3,5-dimethyl-4-octyne-3,5-diol is used in a fountain solution. Other examples illustrate the use of only ethylene oxide derivatives of acetylenic diols.
Although acetylenic diol derivatives containing both ethylene oxide (EO) and propylene oxide (PO) have been taught as a general class of materials, usually as potential extensions of work which had been performed with ethylene oxide derivatives, no actual examples of an acetylenic diol EO/PO derivative based upon 2,4,7,9-tetramethyl-5-decyne-4,7-diol or 2,5,8,11 -tetramethyl-6-dodecyne-5,8-diol have been prepared and evaluated. There are no disclosures of any process which could be used to prepare materials of this type.